Background
In An intro to Minecraft mods, I outline my reasons for choosing the Fabric framework over Forge. Continuing with that same reasoning, this post will be outlining multiple approaches for running a Minecraft server using Fabric (although at a high level, the concepts should still apply to Forge).
You may want to do some research beforehand to determine which mods you want to run on your server, since Fabric mods will only run on a Fabric server, and Forge mods will only run on a Forge server.
If you're not sure what a Minecraft server is, you can simply think of it as a place to house Minecraft mods. To get a better idea of how a server fits into modding in general, read the Fabric Server section of the aforementioned post.
Overview
You might be wondering where the "multiple approaches" bit comes in, since we are only focusing on Fabric. We'll be covering the following ways to host a Fabric server:
Regardless of where the server is hosted, it can be invoked (or "spun up") in multiple ways:
Choosing a server location
In the Development Environment section of the first post, we covered the fact that your development environment matters, in terms of which computer you use. Conversely, the computer you choose to use as your server doesn't matter at all -- so long as it has the proper version of Java and enough RAM to run Minecraft.
Separate machine vs local machine
Speaking of RAM, that is one reason you might choose to run your server on a separate computer; the default amount of RAM allocated to the Minecraft server is 2GB, which your computer may not have to spare.
Even if RAM isn't an issue for you, you may still want a separate machine for other reasons -- a big one being availability; if you want your server to be accessible round-the-clock, you likely want a separate machine. Otherwise, your server goes down if your computer shuts off or loses network connectivity.
On the other hand, if your server needs are more casual and constant availability isn't a concern, then running the server locally (from your main machine) might be enough for you.
A new computer isn't necessary
You also might be thinking, "I can't afford to buy another computer to run a server on". If that's the case, you could explore these options:
Docker
Docker might be a good option if you want to be able to reuse the same server configuration on multiple devices, or if you don't want to alter an existing Java configuration. Here are a few things to note about running a server in a Docker container:
it will still consume RAM on whatever computer is running the container
no Java configuration is required
- Java is automatically installed in the container
Docker containers don't "care" where they are run from
Docker can run from
Here's an example of when you might want to use Docker:
You are testing out a Minecraft server configuration with multiple mods, and multiple custom game settings. You're testing this configuration out on your laptop, but you want to be able to recreate the configuration on another machine without having to install each mod and enable each custom game setting all over again.
This is a great reason to use Docker. At a high level, the configuration would look something like this:
find and download a Docker image that is preconfigured for running a Minecraft server
- think of the image as the blueprint for the container
use the image to run a container
load the mods you want to test into the container via a volume
once you've decided on the game settings and mods you want to use, put instructions on how the container should be run in a docker-compose.yml file
We'll illustrate these concepts with examples later in the Running a Server with Docker section.
Running a Server
Java Prerequisite
If you plan on running a server on a machine other than your own, make sure to install Java on that machine, following the instructions provided by Fabric.
If you're using Docker, make sure the image you're using has the correct version of Java. The image likely has a way to specify a Java version with a tag for the image.
If you're using Linux for your server, the instructions Fabric provides for setting up Java are fairly basic. For more detailed instructions, see Installing Java on Ubuntu.
Loading a mod onto the server
For mods to work on the server, we need to make sure that our Minecraft client has those same mods. More specifically, that means:
you have an installation of the Fabric launcher (client) whose version matches the Minecraft version of your server
- this is the launcher you select when you open the Minecraft application on your computer
the /mods folder for your Fabric launcher installation contains:
the /mods folder for your Fabric server must contain the same .jar files as the /mods folder in the Fabric launcher
In other words, the /mods folder within your Fabric launcher client should have the same contents as the /mods folder on your Fabric server. If you want to read more about the reasoning, check out the Fabric docs on this topic.
once the /mods folders match on the client and server, launch the server
once the server is running, grant op (operator) permissions to necessary player(s)
connect to the server using the Connecting to your server instructions below
verify that you can use the mod
Approach-specific instructions are detailed below.
Running a Server on Linux/MacOS
This is perhaps the most accessible option since it can be run from:
a machine running Linux
a machine running MacOS
Here we'll follow instructions from the Fabric wiki, and walk through them as we go.
If you've been following along, you should already have Java installed. The next step is to go to the server download page and download the relevant version:
mkdir fabric-server
cd fabric-server
curl -OJ https://meta.fabricmc.net/v2/versions/loader/1.19.4/0.14.19/0.11.2/server/jar
ls
fabric-server-mc.1.19.4-loader.0.14.19-launcher.0.11.2.jar
Now that we have the server's .jar file downloaded, we can use the command supplied on the download page to launch the server using that .jar file:
java -Xmx2G -jar fabric-server-mc.1.19.4-loader.0.14.19-launcher.0.11.2.jar nogui
We get an error, which is expected because we need to accept the EULA:
[21:10:21] [main/ERROR]: Failed to load properties from file: server.properties
[21:10:21] [main/WARN]: Failed to load eula.txt
[21:10:21] [main/INFO]: You need to agree to the EULA in order to run the server. Go to eula.txt for more info.
If we inspect the contents of our server folder, we can see that files and directories have been generated as a result of attempting running the server. Among these is the file eula.txt:
ls -la
drwxr-xr-x 4 idev idev 4096 Jun 12 21:10 .fabric
-rw-r--r-- 1 idev idev 158 Jun 12 21:10 eula.txt
-rw-r--r-- 1 idev idev 155095 Jun 12 21:09 fabric-server-mc.1.19.4-loader.0.14.19-launcher.0.11.2.jar
drwxr-xr-x 8 idev idev 4096 Jun 12 21:10 libraries
drwxr-xr-x 2 idev idev 4096 Jun 12 21:10 logs
drwxr-xr-x 2 idev idev 4096 Jun 12 21:10 mods
-rw-r--r-- 1 idev idev 1272 Jun 12 21:10 server.properties
drwxr-xr-x 3 idev idev 4096 Jun 12 21:10 versions
Now we can open that file with our preferred text editor and change false to true:
vim eula.txt
eula=true
Now that we've agreed to the EULA, we can re-run the command to launch the server:
java -Xmx2G -jar fabric-server-mc.1.19.4-loader.0.14.19-launcher.0.11.2.jar nogui
The server starts up this time with no errors:
[21:15:16] [Worker-Main-2/INFO]: Preparing spawn area: 91%
[21:15:16] [Worker-Main-2/INFO]: Preparing spawn area: 94%
[21:15:17] [Worker-Main-5/INFO]: Preparing spawn area: 97%
[21:15:17] [Server thread/INFO]: Time elapsed: 28858 ms
[21:15:17] [Server thread/INFO]: Done (35.063s)! For help, type "help"
Now that the server is running, we can click into the terminal and type op your_player_name
[14:24:08] [Server thread/INFO]: Time elapsed: 8357 ms
[14:24:08] [Server thread/INFO]: Done (10.491s)! For help, type "help"
op awesomeminecraftplayer42023
[14:25:01] [Server thread/INFO]: Made maddoxchunk a server operator
Running a Server on Windows
The Fabric instructions do a pretty good job of walking through this one, but we'll go through the steps here anyway (starting with STEP 3: Install Fabric in the Server Folder):
go here and click the 'download for Windows' button
run the file
select the 'Server' tab
select the version and install the location
press 'Install'
click 'Download server jar'
click 'Generate'
open the folder location where you saved the server to
run the start.bat file
you'll get an error about the EULA
close the terminal
open eula.txt in the server folder that has the start.bat file
change false to true in eula.txt
save and exit the file
run start.bat again
click into the terminal with the server running and type op your_player_name to grant operator permissions
Running a Server with Docker
I won't go over installing Docker, since their official docs should be enough to get you there.
It's worth mentioning that once you have Docker installed, the steps below will work the same (more or less), regardless of your operating system.
Run a Vanilla Minecraft server in a container
Once you've got Docker installed, it's time to download and run a Minecraft server image.
start by going to the documentation for the Docker image we're using
run the listed command
docker run -d -it -p 25565:25565 -e EULA=TRUE itzg/minecraft-server
this runs the container in the background so that our terminal is free to run other commands
confirm the container is running with docker ps
copy the CONTAINER ID from the docker ps command
run docker stop <CONTAINER ID> to stop the container
run docker ps again to confirm the container is not running
Run a Fabric Minecraft server in a container
The docker command above allowed us to run a "vanilla" Minecraft server. However, we are interested in running a Fabric server, so we consult the Types and platforms documentation.
From here we can select 'Fabric' from the menu on the left. We can see a command that instructs us on how to run a Fabric server by using the -e TYPE=FABRIC flag. However, there is something else that's different about this command: it's mounting a volume with -v /path/on/host:/data. Before we run this command, we need to set up that directory on our host machine (the one running Docker).
Mounting a data directory
If we head to the Data directory documentation, we get some instructions on how to do this.
Let's try running a container with an attached data volume, using the supplied command from the Fabric section of the image docs:
mkdir mc-data
docker run -d -v ./mc-data:/data \
-e TYPE=FABRIC \
-p 25565:25565 -e EULA=TRUE --name mc itzg/minecraft-server
Okay, so we've started a container and mounted the volume, but how do we use it?
It's a bit difficult to picture right now, since we're running the container as a background process with the -d flag. Let's try running it again without that flag and see what happens:
docker rm mc
docker run -v ./mc-data:/data \
-e TYPE=FABRIC \
-p 25565:25565 -e EULA=TRUE --name mc itzg/minecraft-server
[init] Running as uid=1000 gid=1000 with /data as 'drwxrwxr-x 2 1000 1000 4096 Jun 15 11:12 /data'
...
[init] ERROR: version lookup failed:
This isn't an error with the volume. We would get the same error if we ran the command without the -v flag. The only reason we didn't see the error before is that we ran the process in the background, so the output wasn't visible.
This error is because we need to specify a Fabric/Minecraft version for the container to run.
Let's try it again, this time using the appropriate flags to specify the version:
docker rm mc
docker run -v ./mc-data:/data \
-e TYPE=FABRIC \
-e VERSION=1.19.4 \
-p 25565:25565 -e EULA=TRUE --name mc itzg/minecraft-server
We still get an error, but this time it's different:
[init] ERROR failed to install Fabric launcher from 1.19.4, LATEST, LATEST
This is yet another misleading error message. In my case, it was happening due to an issue with WSL2. The issue is resolved by deleting the ~/.docker/config.json file.
If you encountered the error above, go ahead and delete the config.json file, then run the commands again to make sure it works:
docker rm mc
docker run -v ./mc-data:/data \
-e TYPE=FABRIC \
-e VERSION=1.19.4 \
-p 25565:25565 -e EULA=TRUE --name mc itzg/minecraft-server
Now that we know we can get the server running, it's time to add our mod.
Loading mods onto the server
Looking again at the Data directory documentation, we can see that the /mods folder lives inside the /data directory, which we have created as mc-data on our host machine.
Speaking of the data directory, if we inspect the contents of mc-data, we can see that the folder is no longer empty since we have successfully run the server:
ls mc-data
banned-ips.json fabric-server-mc.1.19.4-loader.0.14.21-launcher.0.11.2.jar ops.json whitelist.json
banned-players.json libraries server.properties world
crash-reports logs usercache.json
eula.txt mods versions
Recall from Loading a mod onto the server that the /mods folder on our server should match the /mods folder in our Fabric launcher installation. As such, we copy the contents of that folder to our data directory for the container
cp -a /path/to/fabric/launcher/mods .mc-data/mods
Now we are ready to run our server again:
docker rm mc
docker run -v ./mc-data:/data \
-e TYPE=FABRIC \
-e VERSION=1.19.4 \
-p 25565:25565 -e EULA=TRUE --name mc itzg/minecraft-server
Go ahead and connect to your server using the instructions below.
The game loads up when we connect, but we have a problem -- we aren't able to run commands. Normally, we could just go to our terminal and op our player, but things work a bit differently with Docker. Since we are running the server in a container, we don't have direct access to the terminal like we do when we run the server directly in the operating system.
So how do we issue commands to our Docker container? Enter RCON.
RCON
RCON is short for Remote Control, and allows Minecraft commands to be issued remotely.
Okay, but... how do we use it?
Thankfully, the Docker image we're using includes rcon-cli. Let's see it in action:
docker stop mc
docker start mc
Before we can run rcon-cli, we need to wait for server to completely load, since RCON does not become enabled until that point. When you see the following message in the terminal, you're ready to use rcon-cli:
[03:28:23] [Server thread/INFO]: Done (8.096s)! For help, type "help"
[03:28:23] [Server thread/INFO]: Starting remote control listener
[03:28:23] [Server thread/INFO]: Thread RCON Listener started
[03:28:23] [Server thread/INFO]: RCON running on 0.0.0.0:25575
Once the RCON service has started, we can open a new terminal window and use rcon-cli:
docker exec mc rcon-cli op your_player_name
Made your_player_name a server operator
Now that you are an operator, you can use commands in Minecraft. Go ahead and use the appropriate command(s) to test out your mod (if applicable).
Docker Compose
When I originally explained the use cases for Docker, a big selling point was the portability, and the ability to reuse configurations. So far, we haven't seen how Docker can achieve that. We ran a bunch of commands, and even hit some errors in the process.
How can a workflow like that be reusable?
The answer is that it can't, and that's where Docker Compose comes into play.
Now that we have a working configuration, we can package that configuration into a docker-compose.yml file so that we don't have to remember the commands. Instead, we can just point Docker to the docker-compose.yml file.
Let's go through the instructions:
first install Docker Compose by following the instructions here.
make a new directory and change into it
mkdir mc-compose
cd mc-compose
create a docker-compose.yml file and put the following in it
note that the file below is slightly different from the file linked in the documentation (we added the VERSION and TYPE environment variables)
also note that indentation matters in a .yml file
Using an .env file
To make things even more reusable, we can use an .env file located in the same folder as our docker-compose.yml file.
vim .env
VERSION=1.19.4
SERVER_TYPE=FABRIC
DATA_DIR=./mc-data
Now we can update our docker-compose.yml:
version: "3.8"
services:
mc:
image: itzg/minecraft-server
container_name: mc
tty: true
stdin_open: true
ports:
- "25565:25565"
environment:
EULA: "TRUE"
VERSION: "${VERSION}"
TYPE: "${SERVER_TYPE}"
volumes:
- "${DATA_DIR}:/data"
Run the server with docker compose up to make sure the new config works.
Automating RCON
Remember how we had to wait for the server to spin up before we could use rcon-cli? That was kind of annoying. It would be nice if there were a way to automate this.
Thankfully, someone made a pull request, and some new commands were added to the image. These commands allow rcon-cli to run automatically, either when the server starts, or when the game client connects to the server.
We'll keep things simple and just automate the provisioning of operator permissions. In the docker-compose.yml file below, you'll notice a new RCON_CMDS_STARTUP property under environment:
version: "3.8"
services:
mc:
image: itzg/minecraft-server
container_name: mc
tty: true
stdin_open: true
ports:
- "25565:25565"
environment:
EULA: "TRUE"
VERSION: "${VERSION}"
TYPE: "${SERVER_TYPE}"
RCON_CMDS_STARTUP: |-
/op your_username_goes_here
volumes:
- "${DATA_DIR}:/data"
Go ahead and run the container with docker compose up. If you get an error like Additional property RCON_CMDS_STARTUP is not allowed, the issue is likely that something isn't indented properly. Go back into the file and make sure the new command is indented one level in from environment.
But remember, we want this docker-compose.yml file to be as reusable as possible. Once it's complete, any changes that we need to make to the configuration should be done via the .env file. Let's put our player name into the .env file:
vim .env
VERSION=1.19.4
SERVER_TYPE=FABRIC
DATA_DIR=/mnt/c/Users/iDev/fabric-1.19.4-client/
OP_PLAYER=your_username_goes_here
Now we can adjust our docker-compose.yml file accordingly:
version: "3.8"
services:
mc:
image: itzg/minecraft-server
container_name: mc
tty: true
stdin_open: true
ports:
- "25565:25565"
environment:
EULA: "TRUE"
VERSION: "${VERSION}"
TYPE: "${SERVER_TYPE}"
RCON_CMDS_STARTUP: |-
/op ${OP_PLAYER}
volumes:
- "${DATA_DIR}:/data"
Note that the syntax is slightly different for this command, compared to the others. There are no quotes around the command. Using quotes will cause an error.
It's also possible to specify more than one player, but the error handling still needs to be worked out. This means that if you make a typo in one player's name, or one of the players doesn't exist, the entire command will fail.
If you're interested in experimenting with this, the syntax for specifying multiple players is as follows:
OP_PLAYERS=your_user_name_goes_here:player2
Reusing a Docker config
So far, we've seen how using Docker Compose can save us from having to type long complicated commands. We can take it a step further and place our docker-compose.yml file on another machine so that it can run the same container with the same configuration.
First things first, we'll copy the file from our local machine over to a Virtual Private Server that has Docker installed. Also note that a user named mc-admin has already been created on the VPS:
rsync -a ./docker-compose.yml digitalocean.minecraft:/home/mc-admin/vps-mc/
If you're unfamiliar with rsync, here is what the command above does:
takes the docker-compose.yml file in our current directory on the local machine
uses SSH behind the scenes to log into the VPS (digitalocean.minecraft)
creates a directory vps-mc/ on the VPS, under the existing mc-admin user's /home directory
this is why the / is important at the end of the command
without the /, vps-mc will be created as a file instead of a folder
places the docker-compose.yml file in the /home/mc-admin/vps-mc directory of the VPS
Since I've previously configured ssh, I don't need to supply a username and password when I run the command above.
If you haven't configured ssh, it would look more like this:
rsync -a ./docker-compose.yml mc-admin@docker.vps.ip:/home/mc-admin/vps-mc/
If you want to learn how to simply your ssh flow like I have, make sure to check out my Managing SSH Keys post.
Before we run the server, we need to transfer over a few more files and folders:
rsync ./.env digitalocean.minecraft:/home/mc-admin/vps-mc/
rsync -a --mkpath ./mc-data/mods/ digitalocean.minecraft:/home/mc-admin/vps-mc/mc-data/mods/
Now we're ready to run the server on the VPS:
ssh digitalocean.minecraft
cd vps-mc
docker compose up
permission denied while trying to connect to the Docker daemon socket at
unix:///var/run/docker.sock:
Get "http://%2Fvar%2Frun%2Fdocker.sock/v1.24/containers/json?all=1&filters=%7B%22label%22%3A%7B%22com.docker.compose.config-hash%22%3Atrue%2C%22com.docker.compose.project%3Dpi-mc%22%3Atrue%7D%7D":
dial unix /var/run/docker.sock: connect: permission denied
Okay, so we got a permissions error. No biggie, this is a pretty common thing to run into with Docker. I had already configured it on my local machine, but we need to set it up on the VPS.
Enabling rootless Docker
Yes, prefixing Docker Compose command with sudo would fix our issue, but running Docker as root goes against best practices, so we're going to do it the proper way:
You can follow along with this step by viewing the Docker documentation.
first we'll start by updating our package manager
sudo apt-get update && sudo apt-get upgrade
next we'll install the package that Docker tells us we need
sudo apt-get install uidmap
follow the instructions under Distribution-specific hint
sudo apt-get install -y dbus-user-session
the package is already installed, so no need to log out/back in
follow the instructions under the Install section
dockerd-rootless-setuptool.sh install
receive command not found error
continue following instructions: sudo apt-get install -y docker-ce-rootless-extras
received another error: Unable to locate package docker-ce-rootless-extras
switch to the Without Packages tab and run curl -fsSL https://get.docker.com/rootless | sh
The installation was successful, but we have some output to read through:
[INFO] Installed docker.service successfully.
[INFO] To control docker.service, run: `systemctl --user (start|stop|restart) docker.service`
[INFO] To run docker.service on system startup, run: `sudo loginctl enable-linger sharif`
[INFO] Creating CLI context "rootless"
Successfully created context "rootless"
[INFO] Using CLI context "rootless"
Current context is now "rootless"
[INFO] Make sure the following environment variable(s) are set (or add them to ~/.bashrc):
export PATH=/usr/bin:$PATH
[INFO] Some applications may require the following environment variable too:
export DOCKER_HOST=unix:///run/user/1000/docker.sock
Going through the sections of output one by one:
since I want Docker to run when the system starts, I run the provided command
sudo loginctl enable-linger sharif
I need to set both the PATH and DOCKER_HOST environment variables
I'm using zsh and not bash, so environment variables are set differently
I refer to a previous blog post of mine to set the environment variables at the profile level
Now we should be able to run docker compose up from our vps-mc directory again without getting a permissions error.
Connecting to your server
On our computer with Minecraft installed, we can open our Minecraft Launcher, and confirm that we can connect to the server.
select the Fabric Launcher installation
- make sure the version of Minecraft for the launcher aligns with the version of Minecraft for your server
when the game loads, select 'Multiplayer'
accept the warning about third-party online play
select 'Direct Connection'
depending on how you set up your server, you'll need to enter the hostname accordingly
click 'Join Server'
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